The invention relates to mechanical transmissions for transforming the rotational motion to the rotational or reciprocal one, applying the toothed engagement of gears and it can find its application in cylindrical, bevel or planetary gearboxes and rack gears with a high gear ratio, small overall dimensions and a high load carrying capacity.
Along with all its advantages, the commonly used involute gearing possesses the low load carrying capacity, determined by tooth dimensions and, moreover, it has restrictions of the gear ratio in one stage. In practice the gear ratio of a single-stage gearbox seldom exceeds 7. In order to increase the involute gearing load carrying capacity, the tooth module is to be increased, leading to the unreasonable increase of gear dimensions.
The helical Novikov gearing is known (A. F. Kraynev. Reference dictionary on mechanisms, Moscow, Mashinostroyeniye, 1987, p. 242). Its toothed profiles have the contact point, transferring in operation along the line, parallel to gearwheels axes. The gearwheels convex flanks of pitch addendums are interacting with concave flanks of pitch dedendums. For this purpose the profiles are outlined in the end cross-section by circumference arcs with curvatures of opposite signs. The gearing transverse contact ratio is equal or close to zero. Operating smoothness is achieved by the axial overlap, its coefficient being chosen above 1. In comparison with the involute gearing, the Novikov one has twice higher load carrying capacity and possesses the increased efficiency, but unlike the involute one, it is very sensitive to variation of interaxial distance. That is why a higher manufacturing accuracy and increased rigidity of shafts and supports are required here.
The eccentrically cycloidal gearing with curvilinear tooth profiles is known (see Stanovskoy V. V., Kazakyavichyus S. M. et al. New type of gearing with curvilinear toothed profiles. Reference book. Engineering journal, No 9, 2008, pp. 34-39). Its smaller gearwheel has only one helical tooth with the profile in the end cross-section representing the circumference, eccentrically shifted with respect to the gearwheel axis of rotation. The curvilinear helical profile of the gearwheel is generated by a consequent continuous displacement of this circumference along the gearwheel axis with its simultaneous rotation around the same axis. The greater gearwheel tooth profile in the end section is conjugated with the eccentrically shifted circumference of the smaller gearwheel. The profile is plotted as the envelope of the eccentric circumferences family in different meshing phases and it represents the cycloidal curve which is the equidistant of an epitrochoid for the external gearing. The helical curvilinear flank of the second gearwheel teeth is generated similarly by a consequent continuous rotation of cycloidal end sections around the gearwheel axis. The gearing can be applied in cylindrical or bevel gearwheels and in a rack gear. In case of bevel gearwheels engagement the teeth will have the described above shape in sections by an additional cone or in spherical sections with the sphere center in the point of gearwheels axes intersection. The section by an additional cone for bevel gearwheels and the end section for cylindrical gearwheels can be defined by one generalized concept—the principal cross-section.